下面的介绍英文部分摘自Investor.gov，中文为本人翻译，可以以此了解一下。

先来讲一下Stop Order的含义以及需要注意的地方：

A stop order, also referred to as a stop-loss order, is an order to buy or sell a stock once the price of the stock reaches a specified price, known as the stop price. When the stop price is reached, a stop order becomes a market order. A buy stop order is entered at a stop price above the current market price. Investors generally use a buy stop order to limit a loss or to protect a profit on a stock that they have sold short. A sell stop order is entered at a stop price below the current market price. Investors generally use a sell stop order to limit a loss or to protect a profit on a stock that they own.

止损指令是指当股票价格达到特定价格（即止损价格）时买卖股票的指令。一旦达到止损价格，止损指令即变为市价指令。止损价格高于现行市价时，输入买入止损指令。投资人一般利用买入止损指令限制卖空股票的损失或保护卖空股票的利润。止损价格低于现行市价时，输入卖出止损指令。投资人一般利用卖出止损指令限制手中股票的损失或保护手中股票的利润。

Before using a stop order, investors should consider the following:

在使用止损指令之前，投资人须考虑以下几个方面：

Investors should carefully select the stop price they use for a stop order since short-term market fluctuations in a stock’s price can activate a stop order.

投资人应谨慎选择触发止损指令的止损价格，因为股票价格的短期市场波动会激活止损指令。

The stop price is not the guaranteed execution price for a stop order. The stop price is a trigger that causes the stop order to become a market order. The execution price an investor receives for this market order can deviate significantly from the stop price in a fast-moving market where prices change rapidly. An investor can avoid the risk of a stop order executing at an unexpected price by placing a stop-limit order, but the limit price may prevent the order from being executed.

止损价格并不一定就是止损指令的执行价格。止损价格会触发止损指令变为市价指令。在快速变化的市场中，价格变化迅速，投资人就市价指令获得的执行价格会明显偏离止损价格。投资人可以通过止损限价指令规避以意料之外的价格执行止损指令的风险，但是限价可能会阻止命令的执行。

Different trading venues and firms have different standards for determining whether a stop price has been reached. Some use only last-sale prices to trigger a stop order, while others use quotation prices. Investors should check with their brokerage firms to determine which standard would be used for stop orders.

不同的交易场所和经纪公司制定的有关确定是否达到止损价格的标准会有所不同。有些仅通过收盘价触发止损指令，而有些是通过报价触发止损指令。投资人应向经纪公司核实适用于止损指令的标准。

接着介绍一种Stop Order，也就是Trailing Stop Order：

A trailing stop order is a stop or stop limit order in which the stop price is not a specific price. Instead, the stop price is either a defined percentage or dollar amount, above or below the current market price of the security (“trailing stop price”). As the price of the security moves in a favorable direction the trailing stop price adjusts or “trails” the market price of the security by the specified amount. However, if the security’s price moves in an unfavorable direction the trailing stop price remains fixed, and the order will be triggered if the security’s price reaches the trailing stop price.

追踪止损指令属于止损指令或止损限价指令，止损价格并非特定价格，而是规定的百分比或美元，高于或低于证券的现行市价（“追踪止损价格”）。证券价格向有利方向变动时，追踪止损价格通过特定金额调整或“追踪”证券的市价。但是，如果证券价格向不利方向变动，追踪止损价格保持不变，证券价格达到追踪止损价格即触发指令。

Before using a trailing stop order, investors should consider the following:

在使用追踪止损指令之前，投资人须考虑以下几个方面：

Investors should carefully select the trailing stop price they use for a trailing stop order since short-term market fluctuations in a stock’s price can activate a trailing stop order.

投资人应谨慎选择触发追踪止损指令的追踪止损指令价格，因为股票价格的短期市场波动会激活追踪止损指令。

As with stop and stop-limit orders, different trading venues may have different standards for determining whether the stop price of a trailing stop order has been reached. Some exchanges use only last-sale prices to trigger a trailing stop order, while other venues use quotation prices. Investors should check with their brokerage firms to determine which standard would be used for their trailing stop orders.

就止损指令和止损限价指令而言，不同的交易场所制定的有关确定是否达到追踪止损指令的止损价格的标准会有所不同。有些交易所仅通过收盘价触发追踪止损指令，而有些是通过报价触发追踪止损指令。投资人应向经纪公司核实适用于追踪止损指令的标准。

来源：

Investor.gov